Process for dezincing aluminum



March 17, 1936. J, 0. BETTERTON ET M y 2,034,372

' P'ocEss Foa DEzINcI'NG ALUMINUM Filed April 27, 1954 Patented Mar. 17,l 1936 UNITED STATES PATENT oFFIcE PROCESS FOR DEZINCING AL poration of New Jersey Application April 27, 1934, Serial No. 722,623

1 Claim.

This invention relates to the separation and removal of zinc from aluminum.

The invention provides a process for treating zinc-bearing aluminum by which the zinc is' readily and economically removed from alu'- minum' without the loss of any vappreciable amounts of the latter element. In accordance with the invention the impure aluminum, for example, any of various aluminum scrap materials, is treated in the molten state with a liquid metal capable of preferentially dissolving. the zinc from the aluminum but which is itself insoluble in aluminum. The liquid metal containing the zinc is then itself dezinced out of contact with the molten aluminum and recirculated in the system where it dissolves further amounts of zinc, the cycle being repeated until the zinc content of the aluminum is sufficiently depleted.

Although the novel features lwhich are believed to be characteristic of this invention will be particularly pointed out in the claim appended hereto, the invention itself, as to its objects and advantages, and the manner in which it may be carried out may be better understood by refer' ring to the following description taken in connection with the accompanying drawing' form-'- ing a part thereof, in which the single figure is a section through apparatus suitable for practising the process of the invention.

In the drawing, I is a furnace equipped with burnerv II, flue I2 and sloping hearth I3. Adjacent the furnace is an iron rening kettle I4 equipped with stirrer I5 and pump I6 each driven by motors I'I and I8 respectively. A pipe I9 leads from the lowest point of hearth I3 to the bottom of kettle- I4 while another pipe 20 leads from pump I6 to furnace I0 at approximately the bath level of the latter.

Employing such apparatus, the invention may be practised as follows: the aluminum to be dezinced is melted in the furnace IIJ over a layer of liquid lead which is only sparingly soluble in aluminum but in which zinc will readily dissolve. (In the drawing 2| indicates the level of the aluminum bath and 22 the level of the liquid lead.) By operating the pump I5, lead is circu- 4 lated from the kettl'e I4 to the furnace I0 thus allowing lead containing zinc to automatically enter the kettle I4 via pip'e Ill.v The lead is de-` zinced in kettle Il as by reaction with lead chloride indicated by 23 on top of the lead `bath 24 (Cl. i5-58) which reaction is facilitated by operation of stir rer I5. The purified lead is recirculated to the furnace where it dissolves further quantities of zinc` Thecycle is continued until the zinc content of the aluminum has been decreased the 5 requisite amount.

The eiiiciency of the process of the invention is illustrated by the following examples. Scrap aluminum containing 1.66% zinc was melted over lead, the lead dezinced with chlorine gas out m of contact with the aluminum vand the dezincedA lead recirculated as contemplated by the invention. In this manner the zinc content of the aluminum was readily reduced to 0.07% with practically no loss of lead or aluminum.

The present invention provides an extremely satisfactory solution to a problem which has become exceedingly acute due to the constantly increasing zinc content of aluminum products accompanying the repeated reclamation and reuse of that metal. In fact, prior to the invention. considerable care had to be exercised in 'selecting aluminum scrap for treatment as much of it contained such large quantities of zinc that the reclaimed metal was unsatisfactory or totally unfit for many purposes.

While certain novel features of the invention have been disclosed and are pointed out in the annexed claim, it will be understood that various omissions, substitutions and changes m'ay be made by those skilled in the art without departing from the spirit of the invention. For example, cadmium, bismuth or other metals which are relatively insoluble in aluminum but in which zinc readily dissolves may be used instead of lead as the liquid metal. Also, the liquid metal may, if desired, be dezinced by utilizing oxidation or other methods instead of by chlorine or its salts.

What is claimed is:

The process for refining aluminum with respect to zinc as a contaminant which comprises circulating a solvent metal selected from the group consisting of bismuth, cadmium and lead through the body of a bath of aluminum thereby dissolving zinc, separating the solvent metal containing zinc from the aluminum bath, dezincing the solvent metal, and recirculating the dezinced solvent metal through said bath to further decrease the zinc content of the latter.

JESSE O. BE'I'I'EIRTON. ALBERT'J. PHILLIPS. 

